Wednesday, December 09, 2015

Brazil Estimates 500K+ Zika Infections

# 10,786

Yesterday the government of Brazil published a 67 page PDF file (alas, in Portuguese) called Plano Nacional De Enfretamento A Microcefalia(National Plan to Combat microcephaly), that – among other things – contains the Brazil’s first estimate of the burden of the Zika virus since it arrived last spring.

While estimates are exactly that, and should be taken with a sizable grain of salt, if this estimate is even remotely accurate it attests to the rapid spread of the virus across Brazil.

Many cases are mild, or even asymptomatic, and so exact numbers are impossible to obtain. With the rainy (read:mosquito) season running now through March, these numbers are only likely to expand.

These remarkable projections will no doubt ratchet up the level of concern in other South and Central American countries.

The PDF format (via slideshare) makes translations difficult, but we do have a report from Brazil’s MOH Health Blog:

The Ministry of Health published, on Tuesday (08) the Surveillance and Response Protocol to microcephaly occurred related to infection by Zika virus. The material was drawn from the discussions between the Ministry of Health and experts from various fields of medicine, epidemiology, statistics, geography, laboratory, and representatives of Health Secretaries of states and municipalities affected. The protocol contains information, technical guidance and guidelines related to the microcefalias surveillance actions for health professionals and surveillance teams.

Among the guidelines are the definitions of suspected cases of microcephaly during pregnancy, suspected cases during labor or after birth, criteria for exclusion of suspected cases and reporting and laboratory research system. In addition, there are guidelines on how the epidemiological investigation of suspected cases and the monitoring and analysis of data should be made. Finally, the protocol provides information on strengthening the fight against Aedes aegypti.

In this protocol, the head circumference of babies follows standard of the World Health Organization as (WHO), set to 32 cm. Initially, before the unexpected and unusual increase in cases of microcephaly in newborns, the Ministry of Health recommended that the measure of 33 cm were adopted to include a greater number of babies in research to better understand the situation.

It is worth clarifying that the head circumference (HC) varies according to the gestational age of the baby. Thus, most of the children born after nine months of pregnancy, the skull of 33 cm in diameter is considered normal for the Brazilian population, and there may be some variation for shorter depending on the ethnic and genetic characteristics of the population.